Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
One type of wearable device has control electronics and an antenna embedded therein. An external reader may be configured to transmit radio frequency (RF) energy to the wearable device so as to provide power to the wearable device. The combination of the control electronics and the antenna may be configured to receive such RF energy transmitted by the external reader and modify the impedance of the antenna so as to characteristically modify the backscatter from the antenna. In this way, the wearable device may communicate back to external reader.